The present invention relates to a “growing rod” device, namely a device that is adapted to be mounted to a long bone or to the spine of a patient and that incorporates the ability to have its overall length extended (distracted) or reduced (compressed) in situ.
Growing rod devices have been developed for implantation in the spine of a child to correct an abnormal curvature of the spine, such as scoliosis. In devices of this type, a rod assembly is progressively lengthened to reduce the abnormal curvature while allowing the child's body to adapt to the revised spinal position. One typical growing rod device includes of a pair of axially aligned rods, each terminating in an anchor element configured for attachment to the spine. Lengthening of one or both rods requires a surgical procedure to advance the effective rod lengths, usually about every six months. This approach requires multiple surgeries, often over a multi-year period, with the result being the correction of the spine curvature caused by the onset of scoliosis.
While growing rod devices have demonstrated their value in correcting serious spinal deformities, the need for multiple surgeries is highly problematic. There is a significant need for a growing rod device that does not require surgical intervention to adjust the length of the device.